1. Technical Field
The present application relates to pipettors and pipetting, and more particularly to a pipettor including an indicator filter.
2. Background of Related Art
Pipettors are widely utilized in laboratories for taking up and discharging precise quantities of fluid. Automated pipettors generally include a motor for actuating a piston, the piston being housed in a cylinder and open to the tip of the pipettor. Generally, two methods of pipetting are practiced, positive displacement pipetting and air displacement pipetting. In positive displacement pipetting the fluid to be pipetted is in direct contact with the base of the piston and the cylinder in which the piston moves. The piston and walls of the displacement cylinder of the pipettor are therefore exposed, or contaminated, with the fluid being pipetted, which may be unacceptable in certain applications. Positive displacement pipettors should, therefore, be regularly cleaned or should utilize disposable pistons and cylinders to avoid cross-contamination of samples.
The more common method of pipetting is the air displacement method which utilizes an air buffer between the base of the piston and the fluid present in a disposable pipette tip, which is attached to one end of the pipettor. In air displacement pipetting, the piston and cylinder in which the piston moves are not intended to be exposed to the fluid being pipetted, as the fluid is generally confined within the disposable pipette tip. Thus, the piston and cylinder need not be replaced or thoroughly cleaned after every use. Even in air displacement pipetting, however, some contamination of the piston and cylinder may occur if either the fluid itself, or aerosol from the fluid, comes into contact with the piston and/or cylinder. This can occur if the operator inadvertently overfills the disposable tip, or if the fluid is agitated in such a manner as to create aerosol fumes. In such situations the piston and/or cylinder may need to be cleaned or possibly replaced.
It some instances it may be difficult for an operator to determine if the cylinder or piston has become contaminated, especially if contamination is due to aerosols formed by the fluid. In addition, if overfilling has occurred, containing the fluid before it reaches the piston or beyond, would be desirable.
There is therefore a need in the art for a device which indicates contamination of a pipettor to an operator and which helps to limit the extent of overfilling, so as to contain such contamination.